Intraoperative injection of local anaesthetic into the transverse abdominis plane (TAP) after cesarean section (C-section) is equally as effective as using ultrasound to guide the injection, according to research presented at the 2016 Annual Clinical Meeting of the American College of Obstetricians and Gynecologists (ACOG)
Lead author Deepa Maheswari Narasimhulu, MD, Maimonides Medical Center, Brooklyn, New York and colleagues randomised 41 women undergoing elective cesarean delivery to receive either intraoperative TAP administered by the obstetrician prior to closure or ultrasound-guided TAP administered by an anaesthesiologist.
A 21-guage blunt-tipped nerve block needle and 20 mL of 0.5% ropivacaine were used in all procedures.
There was no significant difference in postoperative pain scores between the 2 groups at 4, 8, and 24 hours at rest (4.0±2.7 vs 4.2±2.8, P = .99; 4.0±2.5 vs 3.6±2, P = .98; 3±2.7 vs 2.3±2.3, P = .29) and with coughing (6.0±3.4 vs 6.5±2.7, P = .68; 6.0±3.4 vs 5.4±2.6, P = .57; 6.0±3.3 vs 4.7±2.4, P = .15).
Morphine consumption over 24 hours appeared to be lower in the intraoperative group (28±16.8 mg vs 38.4±23.8 mg, P = .12), but did not reach statistical significance. (Pain measurement is highly subjective, the authors noted, and response to pain medications is highly variable.)
Importantly, intraoperative administration of TAP was about 10 minutes faster than ultrasound-guided administration (2.4±0.5 min. vs 12.3±5 min., P < .001).
Patients at busy surgical centres often must wait for an anaesthesiologist in order to use ultrasound to guide administration of the nerve block. If the block is administered intraoperatively, however, there is no waiting for the obstetrician, explained Dr. Narasimhulu. The wait for an anaesthesiologist to perform ultrasound-guided TAP, she noted, is of no benefit to the patient, and is expensive for the hospital.
Percutaneous injections also represent additional breeches of the skin barrier, and add risk for introducing pathogens, the authors noted, while intraoperative injections use an existing breech.
Additionally, said Dr. Narasimhulu, ultrasound does not work as well with patients who have a high body mass index.
Dr. Narasimhulu said the independent review board initially was hesitant to approve this study, but consented when she produced papers from India and England on the use of the procedure. Now, she said, with the outcomes of the study known, colleagues are readily adopting this simple procedure into their practice.